1. Field of the Invention
The present invention relates to a light emitting device having an element in which a light emitting material is interposed between electrodes, and to electric equipment in which the light emitting device is used in a display portion (a display or a display monitor). In particular, the present invention relates to a light emitting device using a light emitting material which provides electro luminescence (EL) (hereinafter referred to as EL material). Note that an organic electro luminescence display and an organic light emitting diode (OLED) are included in the light emitting device of the present invention.
In addition, the light emitting material which can be used in the present invention includes all light emitting materials for producing light emission (phosphorescence and/or fluorescence) through singlet excitation, triplet excitation, or both excitations.
2. Description of the Related Art
Recently, the development of a light emitting device (hereinafter referred to as EL light emitting device) using a light emitting element (hereinafter referred to as EL element) utilizing an EL phenomenon of a light emitting material is progressed. Since the EL light emitting device is a display device using a self light emitting element, a back light which may be used in a liquid crystal display is unnecessary. Also, since the EL light emitting device has a wide view angle, it has been remarked as a display portion of a portable device to be used in an outdoor.
There is a system using a color filter as a system for displaying a color image in the EL light emitting device. For example, an EL element with white color light emission is formed, and then while color light emitted from the EL element is allowed to pass through a colored layer corresponding to R (red), G (green), or B (blue), so that each color light can be obtained.
When such a system is employed, in conventional, a colored layer was provided corresponding to the position of each pixel on a substrate on which an EL element is formed. Thus, it was necessary to perform a photolithography process at least three times.
However, when the photolithography process is performed three times, there arose problems in that not only a manufacturing process of the EL light emitting device is complicated, but also a significant reduction in its yield may be caused, because the yield of individual photolithography process influences by multiplication. As a result, an increase of a manufacturing cost due to the reduction in the yield and an extension of a manufacturing period became a problem.